[R] Populating then sorting a matrix and/or data.frame
Noah Silverman
noah at smartmediacorp.com
Thu Nov 11 10:30:40 CET 2010
That makes perfect sense.
Since I need to build up the results table sequentially as I iterate
through the data, how would you recommend it??
Thanks,
-N
On 11/11/10 12:03 AM, Michael Bedward wrote:
> All values in a matrix are the same type, so if you've set up a matrix
> with a character column then your numeric values will also be stored
> as character. That would explain why they are being converted to
> factors. It would also explain why your query isn't working.
>
> Michael
>
>
> On 11 November 2010 18:40, Noah Silverman<noah at smartmediacorp.com> wrote:
>> That was a typo.
>>
>> It should have read:
>> results[results$one< 100,]
>>
>> It does still fail.
>>
>> There is ONE column that is text. So my guess is that R is seeing that and
>> assuming that the entire data.frame should be factors.
>>
>> -N
>>
>> On 11/10/10 11:16 PM, Michael Bedward wrote:
>>> Hello Noah,
>>>
>>> If you set these names...
>>>> names(results)<- c("one", "two", "three")
>>> this won't work...
>>>> results[results$c< 100,]
>>> because you don't have a column called "c" (unless that's just a typo
>>> in your post).
>>>
>>>> I tried making it a data.frame with
>>>> foo<- data.frame(results)
>>>>
>>>> But that converted all the numeric values to factors!!!
>>> Not sure what's going on there. If 'results' is a numeric matrix you
>>> should get a data.frame with numeric cols since under the hood this is
>>> just calling the as.data.frame function.
>>>
>>> Michael
>>>
>>>
>>>
>>>
>>>
>>> On 11 November 2010 16:02, Noah Silverman<noah at smartmediacorp.com> wrote:
>>>> Hi,
>>>>
>>>> I have a process in R that produces a lot of output. My plan was to
>>>> build
>>>> up a matrix or data.frame "row by row", so that I'll have a nice object
>>>> with
>>>> all the resulting data.
>>>>
>>>> I started with:
>>>> results<- matrix(ncol=3)
>>>> names(results)<- c("one", "two", "three")
>>>>
>>>> Then, when looping through the data:
>>>> results<- rbind(results, c(a,b,c))
>>>>
>>>> This seems to work fine. BUT, my problem arises when I want to filter,
>>>> sort,
>>>> etc.
>>>>
>>>> I tried (thinking like a data.frame):
>>>> results[results$c< 100,]
>>>>
>>>> But that fails.
>>>>
>>>> I tried making it a data.frame with
>>>> foo<- data.frame(results)
>>>>
>>>> But that converted all the numeric values to factors!!! Which causes a
>>>> whole mess of problems.
>>>>
>>>> Any ideas??
>>>>
>>>> -N
>>>>
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>>
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